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<DIV><FONT size=2>According to the Parts Catalogue 709 is for 18Gx engines, 3911
for 18V engines, that change being in August 71. It doesn't differentiate
between North America and anywhere else, and although North America and
other export markets got HIFs at the same time as the change in engines, the UK
continued with HS carbs until 1974. There were corresponding changes in
the inlet manifolds for both markets, so I suspect the difference is in
the thickness of the mounting tabs on each manifold - matching pairs being
the same thickness, non-matching pairs needing a stepped washer where they share
a bolt, something that is often discussed where modifications to exhaust and
intake are concerned.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>PaulH.</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
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<DIV>I found some HS4s in the dungeon and am replacing the weber and header on
my 1968 GT, but still need the stock exhaust manifold. I see the
manifolds stamped with two numbers: 12H709 and 12H3911. </DIV>
<DIV><FONT size=2 face=Arial></FONT><BR></DIV>
<DIV>Is there a difference between the manifolds? One for HS4s and one
for the HIF carburetor? My 72 MGB has HIFs and the 12H709
manifold. I don’t think it matters.</DIV></DIV></BLOCKQUOTE></BODY></HTML>